Supercritical CO2-induced nondestructive coordination between ZnO nanoparticles and aramid fiber with highly improved interfacial-adhesion properties and UV resistance

Constructing the nondestructively chemical linking between organic phase and inorganic particles has become a hot direction for polymeric surface modification due to the rising demand of anti-ultraviolet (UV) products. Herein, aramid fiber (AF) with coordination of ZnO was developed by a facile supercritical CO 2 (Sc-CO 2 ) drying technique to improve its UV resistance and interfacial-adhesion. Through adjusting the Zn 2+ concentrations, the ZnO nanoparticles (NPs) with different decentralized system were synthesized and deposited to AF surface with stirring and the both were subsequently dried in Sc-CO 2 fluid for bonding. Results indicate that coordination between ZnO NPs and AF was established with the formation of C O Zn bond and the grafting yield of NPs was up to 34.23%. This ZnO-bonded fiber not only shows the greatly enhanced interfacial shear strength (IFSS) and UV resistance overcoming the two inherent defects of AF, but it was also endowed with higher mechanical and thermal performances than the original. For the AF-ZnO fibers in the optimum conditions, its IFSS was severely increased by 68.2%, compared to the pure AF, meanwhile the tensile strength retention after 216 h-UV irradiation is as high as 93.1%. Additionally, those fibers were obtained a better heat-resistant properties and mechanical properties, as the tensile strength and modulus, break elongation and energy were improved by 13.7%, 8.7%, 13.4% and 15.7%, respectively. Therefore, this research shows a fantastic success for nondestructively improving the interfacial-adhesion properties and UV resistance of AF.